1. Field of the Invention
The present invention relates to an image reading apparatus for use in a facsimile apparatus, a copying machine, an optical symbol reading apparatus, or the like and, more particularly, to an image reading apparatus having an excellent conveying efficiency of an original.
2. Description of the Prior Art
Hitherto, an image reading apparatus for use in a facsimile apparatus or the like has an arrangement such as illustrated in, for example, FIG. 1. Practically speaking, a refractive index distributed type lens array 6 (hereinafter, referred to simply as a lens array) is attached to a box 4 of an image reading apparatus 2, and LED arrays 8a and 8b serving as light sources are arranged on both sides of the lens array 6, and a photoelectric converting device array 10 serving as photosensing means is provided at the top of the box 4. A roller 12 is also provided to convey an original 14.
The light beams emitted from the LED arrays 8a and 8b are scattered and reflected by the original 14. The reflected lights are focused onto the photoelectric converting device array 10 by the lens array 6 and are converted to an electric signal, so that the image data on the original 14 is read out.
However, in such an image reading apparatus 2, to obtain a sufficient amount of light upon reading of the image, the LED arrays 8a and 8b are arranged on both sides of the lens array 6 so as to sandwich it and the original is illuminated by these two LED arrays 8a and 8b. Therefore, there is a drawback that when the original 14 is read, the edge of the original 14 comes into contact with the LED array 8b arranged on the paper discharge side, so that this causes what is called a jam state such that the original cannot be conveyed. FIGS. 2A to 2E are cross sectional views of the image reading apparatus 2 showing the occurrence of such a jam state. In these drawings, a reference numeral 16 denotes a paper pressing tool, 18 is an optical axis of the lens array 6, and 20 is a position where the original is read.
In FIG. 2A, the edge of the original 14 is led into the image reading apparatus 2 and then reaches the reading position 20 as shown in FIG. 2B. At this time, the edge of the original 14 may in some instance be peeled off from the roller 12 and be obliquely and upwardly moved as shown in FIG. 2C, depending on the quality or state of the original paper 14. If the original 14 is further conveyed in such a state, the edge of the original 14 is come into contact with the LED array 8b arranged on the paper discharge side as shown in FIG. 2D. Moreover, it becomes impossible to convey the original 14, as shown in FIG. 2E, or the paper conveying state becomes abnormal.
FIGS. 3 and 4 show a second example of such a kind of conventional image reading apparatus. In the diagrams, M denotes an original; a numeral 301 is a conveying roller formed of, for example, rubber to convey the original M in the direction indicated by an arrow; 301A is an axis rotatably supported at predetermined position relative to the main body of the apparatus; and 303 is a reading section provided at a position opposite to the conveying roller 301. The reading section 303 comprises: a leaf spring 305 serving as a pressing member for elastically pressing the original M onto the roller 301 over the whole width of the original; an LED array 307 serving as illumination means for illuminating the original M; a focusing light transmission array 309 to focus the reflected lights from the original M; a converting section 311 provided with photoelectric converting devices for photoelectric converting the focused light; a guide member 312, arranged downstream in the conveying direction of the original, for guiding the edge M.sub.1 of the original to smoothly perform the removal of the original from the reading position; and a supporting member 313 to support these respective parts.
The edge M.sub.1 of the original M pressed onto the conveying roller 301 by the leaf spring 305 is guided by the guide member 312 and is conveyed in the direction of the arrow f as indicated by the broken line in FIG. 4 in association with the rotation of the conveying roller 301 by way of drive means (not shown) for driving this roller. During this process, the surface of the original is illuminated by the LED array 307 and the reflected light is supplied to the photoelectric converting section 311 through the focusing light transmission array 309, so that the image on the original M is sequentially read.
However, in such an image reading apparatus, it is desirable to closely arrange the leaf spring 305 and guide member 312, but the arrangement of these members cannot be entirely arbitrary, because it is necessary to consider both the optical path of the illumination light from the LED array 307 and the optical path of the reflected light to the focusing light transmission array 309. Specifically, it is undesirable to allow an edge 312A of the guide member 312 to be arranged long on the side of the leaf spring 305.
Accordingly, in such an image reading apparatus, it is difficult to assure the complete conveyance of the original M by the guide member 312. In dependence on the inserting state of the original edge M.sub.1 to the side of the reading section 303, the edge can be rolled inside of the reading section 303, so that there is a problem that the abnormal conveyance of the original is likely to occur.